Eductor muffler

Abstract

A gas turbine engine exhaust duct of combination circular and rectangular configuration, and accompanying muffler which provides cooling and silencing of exhaust flow from the gas turbine engine. The arrangement utilizes minimum space without sacrifice of performance.

Having described the invention with sufficient clarity that those skilled in the art may make and use it, we claim: 
     
       1. In combination with a gas turbine engine developing a high temperature, high velocity exhaust gas flow therefrom in a first direction: a compact exhaust duct configured and arranged to smoothly turn said exhaust gas flow to a second direction substantially perpendicular to said first direction, said exhaust duct having sequentially arranged inlet, transition, corner, and outlet sections and a continuous internal passage of substantially constant cross-sectional area extending through said sections, said internal passage being of substantially circular cross-section of a diameter D in said inlet section, of substantially constant rectangular cross-section having a minor dimension of approximately D/4 in said corner and outlet sections, and of a cross-section in said transition section smoothly varying from said circular to said rectangular cross-section, said transition and outlet sections extending respectively in substantially said first and second directions, said corner section smoothly curving from said first direction to said second direction at a substantially constant radius of curvature of approximately D/2, said exhaust duct arranged with said inlet section receiving said exhaust gas flow from said engine. 
     
     
       2. In combination with a gas turbine engine developing a high temperature, high velocity gas flow therefrom in a first direction: a muffler having a primary internal exhaust gas flow path extending a distance of approximately 3D in a second direction generally perpendicular to said first direction, said muffler including means disposed in substantially surrounding relationship to said primary flow path for attenuating sound developed by said exhaust flow; and   an exhaust extending between said engine and said muffler, said exhaust duct having sequentially arranged inlet, transition, corner, and outlet sections and a continuous, smooth-walled, substantially unobstructed, internal passage of substantially constant cross-sectional area extending sequentially through said sections, said internal passage receiving gas flow only from said engine,   said internal passage having a substantially circular cross-section of a diameter D in said inlet section, said inlet section communicating with and receiving said exhaust flow from said engine,   said internal passage being of a cross-section smoothly varying from said circular cross-section to a generally rectangular cross-section in said transition section, said transition section extending generally in said first direction,   said internal passage being of said rectangular cross-section and having a minor dimension of approximately D/4 in said corner and outlet sections, said corner section smoothly curving from said first direction to said second direction at a substantially constant radius of curvature of approximately D/2, said outlet section extending generally in said second direction,   said outlet section defining an outlet port of said exhaust duct spaced from and aligned with said internal flow path of the muffler whereby flow of said exhaust gases from said outlet port to said internal flow path draws in cooling, ambient air flow into said internal flow path for mixture with said exhaust gas flow in said muffler.   
     
     
       3. A combination as set forth in claim 2, wherein said primary internal flow path of said muffler is of generally rectangular cross-section having a minor dimension of approximately 3/4D. 
     
     
       4. A turbine-generator unit comprising: a housing having first, second, and third chambers and an opening between said second and third chambers;   means for admitting a flow of cooling air into said second chamber;   an exhaust port for exhausting heated gases from said third chamber;   an electric generator mounted in said first chamber;   a gas turbine engine mounted in said first chamber in driving relationship with said generator;   an oil cooler in said second chamber for carrying oil from said turbine engine in heat exchange relationship with said flow of cooling air passing into said second chamber;   muffler means in said third chamber communicating with said opening and said exhaust port; and   an exhaust duct in said second chamber for receiving flow of exhaust gases from said turbine engine and carrying the latter towards said opening, said duct being spaced from said opening whereby flow of exhaust gases from said duct through said opening to said muffler draws in a flow of cooling ambient air from said second chamber to intermix with said exhaust gases in said muffler.   
     
     
       5. A unit as set forth in claim 4, further including a second means for admitting a second flow of cooling air into said first chamber for cooling said generator, and a conduit extending from said generator to said third chamber for carrying said cooling flow of air from said generator to said third chamber for exhaust from said housing through said exhaust port. 
     
     
       6. A unit as set forth in claim 4, wherein said exhaust duct is arranged in said second chamber whereby flow of exhaust gases from said duct toward said muffler draws in said cooling flow of air into said second chamber through said heat exchanger and thence out of said second chamber through said opening. 
     
     
       7. A unit as set forth in claim 4, wherein said third chamber is arranged vertically above said second chamber, said engine arranged whereby said flow of exhaust gas therefrom is in a horizontal direction, said exhaust duct operable to turn said exhaust gas flow to a vertical direction for passage through said muffler. 
     
     
       8. A unit as set forth in claim 7, wherein said exhaust duct has sequentially arranged inlet, transition, corner, and outlet sections and a continuous internal passage extending through said sections, said internal passage being of substantially circular cross-section in said inlet section, of substantially constant rectangular cross-section in said corner and outlet sections, and of a cross-section in said transition section smoothly varying from said circular to said rectangular cross-section, said transition and outlet sections extending respectively in substantially said horizontal and vertical direction. 
     
     
       9. A unit as set forth in claim 8, wherein said circular cross-section is of a diameter D, said rectangular cross-section has a minor dimension of approximately D/4, said radius of curvature being approximately D/2, said outlet section having a length in said vertical direction of approximately D/2. 
     
     
       10. A unit as set forth in claim 9, wherein said muffler extends in said vertical direction a height of approximately 3D. 
     
     
       11. A unit as set forth in claim 10, wherein said muffler has a primary internal flow path for carrying said exhaust gases from said second chamber toward said exhaust port, said primary flow path being of substantially rectangular cross-section having a minor dimension of approximately 3/4D. 
     
     
       12. A unit as set forth in claim 11, wherein said muffler includes means substantially surrounding said primary flow path for attenuating sound generated by said exhaust gas flow. 
     
     
       13. A unit as set forth in claim 12, wherein said sound attenuating means includes a perforated wall of substantially rectangular cross-section defining the outer limits of said primary flow path, and sound absorption means disposed exteriorly of said perforated wall. 
     
     
       14. A unit as set forth in claim 13, wherein said sound absorption means includes means defining a plurality of sound absorption compartments each of which communicates with said primary flow path through said perforated wall, and sound absorption material disposed in each of said compartments.